Blowing device



March 22, 1963 W. JILEK [ET/AL BLOWING DEVICE Filed July 18, 1962 WALTERJILEK MEINHARD TRUPPE THEIR ATTORNEYS United States Patent 3,241,825BLOWING DEVICE Walter .lilek and Meinhard Truppe, Linz, Austria,assignors to BOT Brassert Oxygen Technik AG., Zurich,

Switzerland, a company of Switzerland Filed July 18, 1962, Ser. No.210,668 Claims priority, application Austria, July 21, 1961, A 5,620/613 Claims. (Cl. 26634) This invention relates to a blowing device forsupplying the refining agent and the admixtures in carrying outmetallurgical processes, e.g., in refining or pre-refining crude iron,in refining steel, in the preparation of alloys, and like processes inwhich the refining agent is supplied from above.

Blowing devices for use in surface-blowing processes are known whichcomprise a blast tube which conducts the refining gas and terminates ina convergent-divergent or de Laval nozzle. It has been proposed tointroduce finely divided basic substances such as lime under pressureinto the supply conduit of the blowing tube and supply them to the bathas a suspension in the refining gas. These known devices involvedvarious disadvantages. High requirements regarding the purity and thestructure of the admixtures had to be met. If the admixtures containedcombustible impurities such as coal or iron particles, these impuritieswere ignited in contact with the oxygen and often caused a destructionof the hose lines. For this reason nickel-chromium steels had to be usedas a material for the supply conduits, which rendered the equipmentexpensive. Besides, devices of this kind were subjected to considerablemechanical wear.

It has further been proposed to introduce admixtures such as finelydivided lime through separate supply conduits into the expansion zone ofthe refining agent; in this case the admixtures were sucked in and mixedwith the oxygen jet and carried into the zone of reaction of the oxygenjet. This method of working has the disadvantage that part of the energyof the oxygen jet is consumed for the suction effect so that thepressure of impact on the bath is reduced and sometimes becomes lowerthan is permissible for the desired performance of the refining process,If the nozzle blows too gently, slags having very high iron oxidecontents are formed, which necessitates an after-treatment of the steelproduced and results in iron losses.

It is an object of the invention to avoid these disadvantages anddifiiculties. A special aim of the invention is to provide a blowingdevice which allows a controlled supply of the admixtures, without anyrisk of inflammation and without danger of an excessive wear of theconstructive elements, while at the same time the adjustability of theoxygen jet, i.e. the possibility to selectively blow either with a sharpjet or with a gentle jet, is retained. The blowing device according tothe invention is characterized in that the blast tube which terminatesin a convergent-divergent nozzle is arranged in a concentric watercooleddowncomer and adapted to be lifted and lowered therein, the annularspace between the blast tube and the downcomer serving for the supply ofadmixtures. Conveniently the annular space communicates with a storagecontainer for fine-grained or pulverulent admixtures, e.g. CaO, coke,ion ore and the like, which is under no pressure. As the supply iseffected under no pressure, the abrasive action of the admixtures isslight, and the wear of the conduits insignificant.

According to a preferred embodiment of the invention the mouth portionof the blast tube is shaped to form a fitting part which can be insertedinto the mouth portion of the downcomer in such manner that thedowncomer is closed when the blast tube is in the lowered position. The

central blast tube may be adapted to be lifted and lowered by means of aspindle or any other suitable means. The fitting part of the blast tubeand the seat part of the downcomer have a cylindrical or frustro-conicalshape, the two parts corresponding to each other. From the seat of thedowncomer upwards a frustro-conical portion may preferably adjoin, whichpasses into a cylindrical tube of larger diameter. By lifting andlowering the blast tube in the range of the conical portion a valveeffect is produced, as the cross-sectional area of the annular space canbe selectively increased or decreased.

The device according to the invention thus enables free control both ofthe quantity of the admixtures added and of the energy of the blowingjet. The cross section of the downcomer may be dimensioned for maximalsupply rateswhen the central blast tube is in its topmost position; whenthe blast tube is in its lowest position, i.e. when the nozzle tip whichforms the fitting part is inserted in the seat of the downcomer, thesupply of admixtures is interrupted and the nozzle acts as a properconvergentdivergent nozzle.

The blowing device according to the invention is explained more fully inthe accompanying drawing by way of exemplary embodiments.

FIG. 1 is a vertical sectional view of an embodiment having a conicalfitting part and seat; FIG. 2 is a similar representation comprising acylindrical fitting part and seat,

In FIG. 1 numeral 1 designates the blast tube which is arranged in aconcentric downcomer and adapted to be lifted and lowered therein. 3 isthe annular space between the blast tube and the downcomer. The mouthportion 4 of the blast tube has a convergent portion 5 and a divergentportion 6 and thus acts as a convergent-divergent or de Laval nozzle.Over the major portion of its length, i.e., as far as to 7, the blasttube confines a cylindrical cross section; the lower end of the mouthportion 8 is shaped to form a slightly conical fitting part which fitsinto the seat 9 provided at the lower end of the downcomer. As far as to10 the downcomer has a cylindrical cross section. Between the seat 9 andthe cylindrical portion, the conical part 11 is arranged. The downcomer2 is a jacket tube, i.e. it consists of the actual inner tube 2 and theouter tube 12, which tubes are integrally connected at their lower ends.concentrically arranged in the jacket space is a guide tube 13 toprovide for the circulation of a coolant. The lower end 14 of the guidetube is shaped to form a stream-lined guide body. 15 are spacers.

The embodiment shown in FIG. 2 differs from that according to FIG. 1only in that the .blast tube 1 has a cylindrical fitting part 16 whichMs in a seat 17 of the downcomer which has likewise cylindrical shape.In this em.- hodiment the outer wall of the blast tube is cylindricalover its entire length.

The blowing devices illustrated in the drawing are op erated by liftingand lowering the central blast tube by means of a spindle or a similarsuitable means. It is evident that the entire cross-sectional area ofthe annular space is available for conveying the admixtures, when thenozzle tip of the central blast tube is at position 10 or higher. Whenthe blast tube is lowered from this highest position, the annular spaceis continually decreased until, when the fitting part engages in theseat, the supply of admixtures is finally interrupted. From thisposition downwards, the blowing device acts as a properconvergent-divergent nozzle. Owing to the solid construction of themouth portion of the blast tube, damages are reliably avoided.

In the following examples experimental heats which were carried out withthe blowing device according to the invention are illustrated in detail.

Example 1.Refining of steelmaking iron After formation of a charge from5,820 kg. liquid crude iron having a composition of: 4.06% C, 0.73% Si,2.09% Mn, 0.124% P, 0.048% S, and 550 kg. scrap and addition of 50 kg.scarfing scale, 40 kg. bauxite, and 40 kg. fiuorspar, a blowing deviceof the type illustrated in FIG. 1 was entered into the crucible. Thecentral blast tube had an inside diameter above the throttle portion of33 mm. and a nozzle diameter of 21 mm. The length of the convergentportion was 20 mm., and the length of the divergent portion 39 mm. Theinside diameter of the downcomer above the conical portion was 67 mm.The blowing device was adjusted to a distance of 500 mm. above the bathsurface, and blowing started at a pressure of 12 kp./cm. gauge. During aperiod of 20 minutes 450 kg. of line dust was supplied through theannular space. Then the supply of admixtures was interrupted by loweringthe blast tube, and blowing continued for 7 minutes. Finally the blowingdevice was withdrawn, the crucible tilted and a steel sample taken whichhad the following composition: 0.06% C, Si, 0.45% Mn, 0-01 P, 0.015% S.The output was 5,600 kg.=88%.

Example 2.C0nversion of basic Bessemer iron and termination of the heatat a desired carbon content A charge of 6,000 kg. liquid crude ironassaying for 3.72% C, 0.35% Si, 0.40% Mn, 1.760% P. 0.033% S, to which100 kg. bauxite and 50 kg. scarfing scale had been added was blown bymeans of a blowing device as illustrated in the drawing. The distance ofthe blowing device was 400 mm.; oxygen pressure 10 kg./cm. gauge.

During an initial period of 14 minutes 550 kg. lime and 60 kg. sand wereadded through the annular space of the blowing device. By lowering theblast tube into the seat of the downcomer the supply of admixtures wasshut off and the oxygen supply then stopped. 20 kg. of iron ore wasadded in one batch, and during the following 2 minutes the bath wasdeslagged and a preliminary sample taken which had the followingcomposition: 1.92% C, 0% Si, 0.25% Mn, 0.230% P, 0.020% S. Then 50 kg.bauxite and 40 kg. sand were added as new slag-forming agents, andblowing was continued for another 7 minutes, during which period 350 kg.of lime was added through the annular space of the device. Finally theblowing device was withdrawn and a steel sample taken which had thefollowing composition: 0.40% C, 0% Si, 0.18% Mn, 0.020% P, 0.017% S. Theoutput was 5,150 kg. of steel=85.7%.

Example 3.Carbarizing and heating of a melt A charge of 5500 kg. ofsteel having the following composition: 0.04% C, 0% Si, 0.35% Mn, 0.015%P, 0.017%

S, and a temperature of 1540 C. was to be carburized to 1% carbon andthe temperature raised. The blowing device illustrated in the drawingwas introduced into the crucible, the distance from the bath adjusted to400 mm., and the oxygen pressure controlled to 5 kg./cm. gauge. During aperiod of 9 minutes normal m. of oxygen were blown and 220 kg. pitchcoke meal supplied through the annular space of the blowing device.Blowing was terminated, the blowing device withdrawn, and a steel sampletaken, which had the following composition: 1.02% C, 0% Si, 0.28% Mn,0.018% P, 0.019% S. The temperature was 1580 C.

What we claim is:

1. A blowing device for supplying an oxygen-containing refining gas andadmixtures in surface-blowing processes, comprising a blast tubeterminating in a convergentdivergent nozzle and a downcomerconcentrically surrounding the blast tube to provide for an annularspace, said blast tube being adapted to be lifted and lowered withinsaid downcomer, said blast tube serving for the supply of the refininggas and said annular space between said blast tube and said downcomerserving for the supply of admixtures in the lifted position of saidblast tube, said downcomer including a downwardly and inwardly shapedport-ion adjacent the mouth portion of the downcomer adapted to directthe admixtures into the refining gas supplied from the nozzle of theblast tube, the mouth portion of the blast tube being shaped to form afitting part adapted to be inserted into the mouth portion of thedowncomer, which forms a seat part, the annular space being closed whenthe blast tube is in the lowered position.

2. A blowing device as set forth in claim 1, wherein the fitting part ofthe blast tube and the seat part of the downcomer are of cylindricalshape, the two parts being complementary to each other.

3. A blowing device as set forth in claim 1, wherein the fitting part ofthe blast tube and the seat part of the downcomer are of frustro-conicalshape, the two parts sloping downwardly and inwardly and beingcomplementary to each other.

References Cited by the Examiner UNITED STATES PATENTS 2,805,147 9/1957Sch'reiber 26634 X 2,829,960 4/1958 Vogt 266-34 X 3,130,252 4/1964 Metz266-35 J OHN F. CAMPBELL, Primary Examiner.

WINSTON A. DOUGLAS, JAMES H. TAYMA-N, JR.,

Examiners.

1. A BLOWING DEVICE FOR SUPPLYING AN OXYGEN-CONTAINING REFINING GAS ANDADMIXTURES IN SURFACE-BLOWING PROCESSES, COMPRISING A BLAST TUBETERMINATING IN A CONVERGENTDIVERGENT NOZZLE AND A DOWNCOMERCONCENTRICALLY SURROUNDING THE BLAST TUBE TO PROVIDE FOR AN ANNULARSPACE, SAID BLAST TUBE BEING ADAPTED TO BE LIFTED AND LOWERED WITHINSAID DOWNCOMER, SAID BLAST TUBE SERVING FOR THE SUPPLY OF THE REFININGGAS AND SAID ANNULAR SPACE BETWEEN SAID BLAST TUBE AND SAID DOWNCOMERSERVING FOR THE SUPPLY OF ADMIXTURES IN THE LIFTED POSITION OF SAIDBLAST TUBE, SAID DOWNCOMER INCLUDING A DOWNWARDLY AND INWARDLY SHAPEDPORTION ADJACENT THE MOUTH PORTION OF THE DOWNCOMER ADAPTED TO DIRECTTHE ADMIXTURES INTO THE REFINING GAS SUPPLIED FROM THE NOZZLE OF THEBLAST TUBE, THE MOUTH PORTION OF THE BLAST TUBE BEING SHAPED TO FORM AFITTING PART ADAPTED TO BE INSERTED INTO THE MOUTH PORTION OF THEDOWNCOMER, WHICH FORMS A SEAT PART, THE ANNULAR SPACE BEING CLOSED WHENTHE BLAST TUBE IS IN THE LOWERED POSITION.